Hello and thanks for using Just Answer.I will try my best to help you with your question.
You will need to check and see if you are getting power at the small post on the starter relay (solenoid).
The small post gets power from the ignition switch when you try to start the truck. See if you are getting power at the small post on the relay.
If not, let me know, we will have to check the ignition switch. They are know to come apart and cause the same problem.